[ARC5] Crystal Question

[Henry Mei'l's]

I'm sure I tried to use a quartz crystal as a detector when I was a kid  --  
I tried just about everything.
Black and brown coal did NOT work. Also tried all kinds of rocks, including 
those with quartz particles and also flint.
Think my carborundum sharpening stone did work -- carbarundum was a detector 
type used in xtal sets. I believe
DC voltage was applied across this type of detector, way back when.
Pretty sure the quartz didn't work BUT a rusty razor blade using a saftey 
pin as cats whisker did work -- pretty sure
I read that this was used in foxhole radios-- similar to what Robert 
mentions.
Just two metal objects, lightly touching, often worked, too.
If I remember correctly, pencil lead and/or a lead
pencil-stripe on paper also worked, sometimes  -- think I also tried the 
carbon rods from dry cells because you could
make a crude carbon microphone by resting a needle across two of these 
rods -- but don't recall if could detect.
Plug-in radar crystals, of course worked perfectly.

Henry M., Cph.

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "Robert Eleazer" <releazer at earthlink.net>; "Discussion of AN/ARC-5 
military radio equipment." <arc5 at mailman.qth.net>
Sent: Thursday, November 11, 2010 6:29 PM
Subject: Re: [ARC5] Crystal Question


> On 11 Nov 2010 at 12:08, Robert  Eleazer wrote:
>
>> I did some looking on that website where the B-26 radio compartment
>> pictures are and found that someone has asked an interesting question.
>>
>> It seems they salvaged some parts from some warbird crash sites in
>> Florida and found some radio crystals. The one he shows looks like it
>> is out of an SCR-522 . The guy who found them wants to use these to
>> make a WWII style "foxhole radio" crystal radio receiver and is asking
>> for help on how to do that.
>
> Obviously, we have a misunderstanding of the two different meanings of
> "crystal" in this case.
>
>>
>> It never occurred to me that a radio crystal might work as a detector
>> in a crystal set. Is this possible?
>
> Hmmm....I would think not, although I have not tried it.
>
>> And did the improvised crystal
>> sets in WWII use radio crystals?
>
> Not to my knowledge: most often they used a Gillette "Blue Blade" and a 
> bit
> of sharpened pencil lead as the "cat's whisker"
>
>> I guess that crystals from downed
>> aircraft and wrecked tanks were probably available on the battlefield
>> in WWII.
>
> Very often.
>
> The "Foxhole Radio" was most often a simple "crystal" set which used the
> Gillette "Blue Blade" (often included in "C" rations) as the "active 
> element",
> and a bit of sharpened pencil lead with a stiff wire wrapped around it as 
> the
> "cat's whisker", or, if it was available, a needle or some other sharp 
> object.
> The earphone was often taken from a field telephone. The Gillette "Blue
> Blade" had "hot spots" on it due to the blue coating on the steel blade.
>
> I suspect that there is a misunderstanding by the "denizens" of that list 
> you
> mention above. They are using the term "crystal" in the wrong sense, or,
> rather mistaking a frequency determining "crystal" for a "crystal 
> detector" or
> diode.
>
> Obviously, they are not the same.
>
> Ken W7EKB
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